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2004 Forester XT
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Discussion Starter · #1 ·
I have seen similar posts about this in the past but I am not sure that I see anything that accurately describes this scenario.

Using LED headlight bulbs works fine (high and low beam functionality) but when I activate my fog lamps the trouble starts. The brights symbol stays dimly lit when low beams are on and when pulling the stalk for high beams there are no high beams whatsoever....everything goes dark!

I think there is a way to mitigate this using some harness and boy am I capable of doing it but I am lazy and want to be informed first.

I love LED reliability and it is such a nice feeling to not have performance halogens burning out more often than I like and at the worst possible time....usually on a back country road or when I bring my car to the inspector who will kindly change the bulb with some garbage laying around for $80.

I don't want to get into conversations about LED bulbs in reflector housings so please stay on track.

Has anyone come across this weird issue?

Thanks.
 

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1,506 Posts
I don't think high beams and fog lights are allowed at the same time. Or maybe Subaru alters the voltage to dim the mainbeams.
LEDs are often setup in a digital way, either on, or off, and if the voltage is wrong they won't react like a filament, they will just go off, or some other malfunction.

Your car was clearly not designed for LEDs. Neither the reflector housings, nor the electrical system.
 

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2017 Forester XT Touring
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1,592 Posts
In my experiments to find a good LED for my motorcycle with an old H4 headlight design, I ran into a couple of things that might contribute to your issue. I went through about 10 different styles of LED headlight to find something that would fit in the limited space, and would throw a good beam pattern without being a problem for other drivers. One thing that might be your issue is the behavior of the LEDs when using high beam. Some of them worked "normally" where they switched between the high and low emitter when I switched the high beam on. Others kept the low beam emitter on and also ran the high beam emitter. In some cases, this might cause issues with the vehicle electrical system, if electricity fed back into the low beam part of the system. I don't know if it did in my case, because on my motorcycle, it wasn't also switching fog lights on and off. Riding a motorcycle in deer country, every bit of light is a blessing, so I actively looked for LEDs that kept both beams on. But in a (only slightly) more complicated car electrical system, I could see it causing issues.

I too, am tired of the "reflector housing" whining, since, if you take the time and effort, it can be done well without causing an issue for oncoming drivers. And I've watched the tech evolve really well, so now it's pretty darn easy to get LEDs that work just fine. I just upgraded my 2003 Ford E350 to LEDs using 9007 inserts. :p
 

· Super Moderator
2001 Forester S, 4EAT
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6,597 Posts
Fog and High beams make no sense and cars DO NOT allow you have both on at the same time. Driving in fog you want low beam and fogs only, driving with High Beams on during fog results in the fog itself reflecting the light back to you the driver and you not seeing further down the road at all.
 

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2004 Forester XT
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972 Posts
Discussion Starter · #6 ·
@bman400 I am aware of this. I might have explained this incorrectly. Another way of looking at this is attempting to use the high beams with the fogs on should simply turn the fogs off. The high beams should not turn off. The fogs should turn off.

With the LED bulbs in place pulling on the high beam stalk results in no lights at all with the high beams on.

The additional symptom is that the brights symbol on the dash glows at 50% even when the brights are not activated.

There are similar posts to this but the symptoms and conclusions/remedies seem to vary.

In my experiments to find a good LED for my motorcycle with an old H4 headlight design, I ran into a couple of things that might contribute to your issue. I went through about 10 different styles of LED headlight to find something that would fit in the limited space, and would throw a good beam pattern without being a problem for other drivers. One thing that might be your issue is the behavior of the LEDs when using high beam. Some of them worked "normally" where they switched between the high and low emitter when I switched the high beam on. Others kept the low beam emitter on and also ran the high beam emitter. In some cases, this might cause issues with the vehicle electrical system, if electricity fed back into the low beam part of the system. I don't know if it did in my case, because on my motorcycle, it wasn't also switching fog lights on and off. Riding a motorcycle in deer country, every bit of light is a blessing, so I actively looked for LEDs that kept both beams on. But in a (only slightly) more complicated car electrical system, I could see it causing issues.

I too, am tired of the "reflector housing" whining, since, if you take the time and effort, it can be done well without causing an issue for oncoming drivers. And I've watched the tech evolve really well, so now it's pretty darn easy to get LEDs that work just fine. I just upgraded my 2003 Ford E350 to LEDs using 9007 inserts. :p
Thanks for this. So you aren't one of Daniel Stern's many cousins? :ROFLMAO:
 

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2007 Forester Sports XT 4EAT
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· Administrator
2016 & 2018 2.5i Premium CVT
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Yes, the interconnection is pretty inscrutable. It’s part of the logic that only lets fogs come on with low beams. It was strange to see that implemented on the actual power side of the circuitry than in a separate control circuit. It allows for weird interactions.
 

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2021 Forester Limited
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2,560 Posts
Light Emitting Diode

Key word Diode. Depending on how the circuit cancels the fogs when high beams are selected, the LED bulbs might be blocking the flow of current in a way they are simply cancelling themselves out.

@2004XT_Auto didn't mention if the fog bulbs were incandescent or LED.
 

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2020 Sport
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490 Posts
I had LED Low beam and Fog lights for two years, no issues. Changing out the tiny 5W C light bulbs, next thing I know I had to have my subie towed to dealership for a colonoscopic without painkiller to reprogram my key fobs....
 
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